Disturbed sleep represents a growing public health concern. Research shows that sleep problems are increasing and are linked to reduced productivity, increased traffic accidents, and increased medical illness. Sleep problems are also a modifiable risk factor for psychiatric illness. The development of inexpensive and validated measures of sleep disturbances is important for early identification, monitoring and treatment of sleep problems. Existing self-report measures of sleep disturbance have been criticized for not comprehensively measuring sleep problems and for not modeling the underlying dimensions of sleep disturbances. The long-term objective of this project is to validate the Iowa Sleep Disturbances Inventory (ISDI). The ISDI is a factor analytically derived instrument with 11 scales that comprehensively measure sleep distrubances (e.g., Insomnia, Nightmares, Movements). These scales are internally consistent and show good discriminant validity. This project proposes to continue the validation process of the ISDI by examining short-term retest stability, convergent and discriminant validity and criterion validity. Beyond this clinical goal, the project also has several theoretical objectives, including examining the differential relations between psychopathology and sleep disturbances and explicating the hierarchical structure of sleep disturbances. The Specific Aims are to (1) examine the short-term retest stability of the ISDI, (2) determine the structure of sleep disturbances by conducting exploratory factor analyses on the ISDI scales, (3) determine how specific sleep disturbances relate to depression, anxiety, substance use, and schizotypy/dissociation, (4) examinethe convergent and discriminant validity of the ISDI with a corresponding clinical interview based on the ISDI scales, (5) establish the criterion validity of the ISDI by correlating ISDI scales with psychological diagnoses from a structured clinical interview and (6) use confirmatory factor analysis to test the model of sleep disturbances obtained in the exploratoryfactor analyses. This project will be conducted with two independent studies. Study 1 will be conducted with a large student sample (N = 300) and will address Specific Aims 1-3. Study 2 will be conducted with a community sample (N = 150) and will address Specific Aims 4-6. The proposed project is necessary for the continuing validation of the ISDI. In addition, this project will result in the creation of a corresponding clinical interview that can be used by sleep researchers and clinicians to identify sleep disturbances. This project will significantly advancethe study of sleep and psychopathology by clarifying the structure of sleep disturbances and the relations between specific sleep disturbances and psychological disorders.